1. Field of the Invention
This invention relates to an adsorption system for continuous bulk separations where separation of a species in a fluid stream is accomplished through continuous selective adsorption onto an adsorbent and subsequent desorption of the species from the adsorbent.
2. Description of the Related Art
The potential of adsorption systems for bulk separations has not been realized on industrially significant scales. Despite inherently low thermal efficiencies, distillation is still the operation of choice for bulk separation of a broad range of compounds. Adsorption separations can be carried out with greater thermal efficiencies, but they typically involve higher capital cost, batch wise operation, and are relatively unfamiliar technologies in the bulk separations industry.
Rotary solvent concentrator wheels are a well-established technology for the removal of solvent vapors in automotive spray booth air; i.e., for concentration of the volatile organic compounds (VOCs) to permit economical incineration. The rotary wheel includes an adsorbent material through which a high volume of VOC-laden air is passed at near ambient temperature. The wheel rotates, exposing about 330° of the arc to the contaminated air stream, resulting in capture of the VOCs on the adsorbent and discharge of clean air to the environment. As the wheel continues to rotate, the adsorbent passes through a regeneration zone, covering about 30° of the arc, through which a much lower volume of hot air (e.g., at a temperature of about 120° C.) is passed. The captured VOCs are desorbed into the hot air stream, which is passed to an incinerator for destruction of the VOCs. In essence, about a 20:1 concentration of the VOCs is obtained, which makes possible the economical incineration of the VOCs. U.S. Pat. No. 5,693,123 describes the use of such a rotary concentrator with extruded adsorbent blocks for removal of impurities from gas streams.
However, there is still a need for an improved adsorber system where separation of a species in the fluid stream is accomplished through continuous selective adsorption onto an adsorbent and subsequent desorption of the species from the adsorbent.